Scroll down on the left to find the Character class and the String class. When you click on these, all the constructors and methods will show in the main frame.

String is a class. Character is a class. When you make a new one (ex: String str = "this is a string") it is called an object. What I told you to use were methods. They are called methods in Java, not functions, though they are essentially the same thing and I continually use the terms interchangeably.